JP2010008799A - Charging unit, process cartridge, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging unit which can maintain superior charging characteristics by keeping the outer surface of the charging roller always clean, and also provide a process cartridge and an image forming device both incorporating this charging unit. <P>SOLUTION: This charging unit has an application roller 104 turning in contact with the charging roller 101 in the same direction (the arrow C direction) as this charging roller 101 turning in the arrow B direction, a cleaning liquid recovery roller 105 disposed downstream in the turning direction B of the charging roller 101 and turning in the direction (the arrow D direction) opposite to the turning direction (the B direction) of the charging roller 101. The cleaning liquid 106 applied to the outer surface 101d of the charging roller 101 is absorbed and recovered by the recovery roller 105 disposed downstream in the turning direction of the application roller 104. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charging device mounted on an image forming apparatus such as a copying machine, a printer, or a facsimile, and more particularly to cleaning of an electric resistance adjusting unit of the charging device. The present invention also relates to a process cartridge and an image forming apparatus provided with the charging device.

Conventionally, in an image forming apparatus using an electrophotographic system such as a copying machine, a laser beam printer, a facsimile, etc., when an electrostatic latent image is formed on the surface of the image carrier, charging that uniformly charges the surface of the image carrier. The device is in use.
FIG. 10 is a schematic configuration diagram of a conventional electrophotographic image forming apparatus. Referring to FIG. 10, reference numeral 11 denotes a drum-shaped photoconductor that rotates in the direction of an arrow as an image carrier having an electrostatic latent image formed on the surface thereof. Reference numeral 12 denotes a charging roller which is a charging device that is arranged in contact or close to the surface of the photosensitive member 11 to uniformly charge, and L denotes exposure of a laser beam corresponding to the image information of the document or reflected light of the document. Reference numeral 14 denotes a developing roller which is a toner carrying member for adhering the toner 15 to the electrostatic latent image on the photosensitive member 11, and reference numeral 16 denotes a transfer roller which is a transfer member for transferring the toner image on the photosensitive member 11 to the recording medium 17. It is. Reference numeral 18 denotes a cleaning blade for removing toner remaining on the surface of the photoconductor 11 after the transfer process from the surface of the photoconductor 11. Reference numeral 19 denotes a waste toner in which the toner remaining on the photosensitive member is removed by the cleaning blade 18 and is accommodated in the cleaning device 21, and reference numeral 20 denotes a developing device in which the developing roller 14 and the toner 15 are accommodated. In FIG. 10, functional units normally required in other electrophotographic image forming processes are omitted for simplification of the drawing.

In such an image forming apparatus, an image is formed by the following means.
1. The charging roller 12 charges the surface of the rotating photoconductor 11 to a desired potential.
2. The photosensitive member 11 is irradiated with exposure L from an exposure device (not shown) to form an electrostatic latent image corresponding to a desired image on the photosensitive member 11.
3. The developing roller 14 develops the electrostatic latent image on the photoconductor 11 with toner, and forms a toner image (developed image) on the photoconductor 11.
4). The transfer roller 16 transfers the toner image on the photoconductor 11 to the recording medium 17.
5). The cleaning device 21 removes the toner that is not transferred and remains on the surface of the photoconductor 11.
6). The recording medium 17 to which the toner image is transferred by the transfer roller 16 is conveyed to a fixing device (not shown).
7). The fixing device heats and pressurizes the toner image on the recording medium 17 and fixes it on the recording medium 17.
By repeating steps 1 to 5 above, a desired image is formed on the recording medium 17.

As a charging method using a charging roller, as shown in Patent Document 1, a contact charging method in which a charging roller 12 is brought into contact with a photoreceptor 11 is known. However, the contact charging method has the following problems.
1. Charging roller traces (occurred because substances constituting the charging roller 12 ooze out from the charging roller and transfer to the surface of the photoreceptor 11) are formed on the recording medium 17.
2. A charging sound (which occurs because the charging roller 12 in contact with the photoconductor 11 vibrates when an AC voltage is applied to the charging roller 12) is generated as noise.
3. The residual toner on the photoconductor 11 adheres to the charging roller 12, resulting in a decrease in charging performance (particularly, toner adhesion is more likely to occur due to the above-described oozing).
4). The substance constituting the charging roller 12 is attached to the photoreceptor 11.
5). When the photoreceptor 11 is stopped for a long time, permanent deformation occurs on the outer peripheral surface of the charging roller 12.

As a method for solving such a problem, a proximity charging method in which the charging roller 12 is brought close to the photoreceptor 11 has been devised. For example, in Patent Document 2, an electrical resistance adjustment layer that charges the surface of the photoreceptor 11 is formed on the outer peripheral portion of the charging roller 12, and the diameter of the electrical resistance adjustment layer is larger than that of the electrical resistance adjustment portion at both axial ends. A structure in which a large ring-shaped gap holding member is press-fitted is known.
In this charging roller, the gap holding member and the photoconductor 11 are brought into contact with both ends of the photoconductor 11 that do not contribute to image formation, and a gap is formed on the surface of the electric resistance adjusting layer and the photoconductor. The surface of the photoreceptor is to be charged by the electric resistance adjusting layer in a non-contact state with the electric resistance adjusting layer.
In the device disclosed in Patent Document 2, it is possible to perform the charging process in a non-contact state between the photoconductor and the electric resistance adjusting layer, so that it is possible to satisfactorily improve the defects of the contact-type charging roller. . However, in the device described in Patent Document 2, foreign matter having the same degree of toner adheres to the surface of the electric resistance adjusting layer, and due to the attachment of the foreign matter, the surface of the photosensitive member becomes non-uniformly charged and an abnormal image is generated. Such problems arise.

As a method of charging the photoconductor to form an electrostatic latent image on the surface of the photoconductor using a charging roller, there are a DC charging method and an AC charging method, and the AC charging method is currently the mainstream. The AC charging method is a charging method in which an oscillating voltage obtained by superimposing an AC voltage on a DC voltage corresponding to a desired charging position is applied to a charging roller.
However, when the AC charging method is used continuously, the generation of ozone is recognized, and furthermore, the AC electric field causes the vibration voltage between the photosensitive member and the charging roller to cause toner and toner additives to be electrically and mechanically applied to the surface of the charging roller. It stays due to mechanical vibration, and the surface of the charging roller becomes dirty and the surface of the photoreceptor is contaminated. In particular, in the non-contact charging method, the surface contamination of the charging roller, the progress of contamination on the surface of the photosensitive member, and the non-uniform charging on the surface of the photosensitive member due to the contamination of the charging roller are It is also greatly affected by uniformity.
To prevent such contamination of the charging roller, the sponge roller is brought into contact with the outer peripheral surface of the charging roller, and foreign matter adhering to the surface of the charging roller is transferred to the sponge roller to remove and clean the foreign matter from the surface of the charging roller. It has been proposed to improve the charging non-uniformity of the charging roller (see, for example, Patent Document 3).
JP 2005-24830 A JP-A-2005-91818 JP 2002-49220 A

However, in the device disclosed in Patent Document 3, the sponge roller is brought into contact with the outer peripheral surface of the charging roller, and the foreign matter attached to the surface of the charging roller is transferred to the sponge roller to remove the foreign matter. There is a problem that surface cleaning becomes insufficient. That is, since the sponge roller is always in sliding contact with the outer peripheral surface of the charging roller, the foreign matter transferred to the sponge roller may be transferred again to the charging roller, resulting in insufficient cleaning of the surface of the charging roller. In particular, it becomes remarkable when the foreign matter collecting ability of the sponge roller is lowered with time.
The present invention has been made in consideration of the above circumstances, and a charging device capable of maintaining good charging characteristics by always maintaining the outer peripheral surface of the charging roller to be a clean surface, and a process cartridge including the charging device An object of the present invention is to provide an image forming apparatus.

In order to solve the above-mentioned problems, the invention of claim 1 includes a charging layer for charging a surface of an image carrier formed on a rotating shaft, and the charging attached to both ends of the charging layer on the rotating shaft. In the charging device including a charging roller having a gap holding member having a larger diameter than the layer, a cleaning liquid for separating the foreign matter adhering to the outer peripheral surface from the outer peripheral surface is disposed on the outer peripheral surface of the charging layer. A cleaning liquid application unit that applies the entire length in the rotation axis direction of the outer peripheral surface of the charging layer, and the rotation axis direction of the outer peripheral surface of the charging layer on the downstream side of the rotation direction of the charging roller with respect to the cleaning liquid application unit And a cleaning liquid recovery means for recovering the cleaning liquid applied to the outer peripheral surface of the charging layer in sliding contact with the entire length.
According to a second aspect of the present invention, in the charging device according to the first aspect, the cleaning liquid is applied to the charging layer by extending the application portion of the cleaning liquid application means so as to contact the outer peripheral surface of the gap holding member. And an outer peripheral surface of the charging layer and the gap holding member by applying to the outer peripheral face of the gap holding member and extending the recovery portion of the cleaning liquid collecting means so as to be in sliding contact with the outer peripheral face of the gap holding member. The cleaning liquid applied to the liquid is collected.
According to a third aspect of the present invention, in the charging device according to the first or second aspect, the cleaning liquid recovery means absorbs a cleaning liquid formed on a rotating shaft disposed in parallel with the rotating shaft of the charging roller. A cleaning liquid recovery roller that rotates while pressing the outer layer of the charging roller on the outer peripheral surface of the charging roller, and is held in contact with the cleaning liquid absorption layer of the cleaning liquid recovery roller and held by the cleaning liquid absorption layer It has a cleaning liquid recovery part for recovering the liquid.

According to a fourth aspect of the present invention, in the charging device according to the third aspect, the cleaning liquid recovery portion is formed on a rotating shaft disposed in parallel with a rotating shaft of the cleaning liquid recovery roller. A cleaning liquid transfer roller member that rotates while pressing a layer against the cleaning liquid absorption layer, a recovery blade member that presses the tip surface against the cleaning liquid absorption layer and collects the cleaning liquid from the cleaning liquid absorption layer, and a tip It is a cleaning liquid recovery member of any one of the suction members that sucks the cleaning liquid from the cleaning liquid absorption layer by bringing the portion into pressure contact with the cleaning liquid absorption layer.
According to a fifth aspect of the present invention, in the charging device according to the fourth aspect, the recovery unit is the cleaning liquid transfer roller member, and the cleaning liquid transfer roller member is the same as the rotation direction of the cleaning liquid recovery roller. It is rotated in the direction.
According to a sixth aspect of the present invention, in the charging device according to any one of the third to fifth aspects, the cleaning liquid absorbing layer of the cleaning liquid recovery roller is made of a foam.
According to a seventh aspect of the present invention, in the charging device according to the sixth aspect, the foam is formed of a resin.
According to an eighth aspect of the present invention, in the charging device according to any one of the third to seventh aspects, the cleaning liquid recovery roller is rotated in a direction opposite to a rotation direction of the charging roller. .

According to a ninth aspect of the present invention, in the charging device according to any one of the first to eighth aspects, the cleaning liquid application unit is formed on a rotation shaft disposed in parallel to the rotation shaft of the charging roller. A cleaning liquid supply having a cleaning liquid application roller that rotates while contacting the cleaning liquid holding layer that is in contact with the outer peripheral surface of the charging layer of the charging roller, and that supplies the cleaning liquid to the cleaning liquid holding layer of the cleaning liquid application roller It has the means.
According to a tenth aspect of the present invention, in the charging device according to the ninth aspect, the cleaning liquid holding layer is made of a foam formed of a resin.
The invention of claim 11 is a process cartridge comprising an image carrier and a charging device for uniformly charging the surface of the image carrier, wherein the charging device is integrated with the image carrier. The charging device is the charging device according to any one of claims 1 to 10.
According to a twelfth aspect of the present invention, an image carrier, a charging device for uniformly charging the surface of the image carrier, and light according to image information are applied to the surface of the image carrier charged by the charging device. An exposure device for forming an electrostatic latent image on the surface of the image carrier by irradiation and a developing device for supplying toner to the electrostatic latent image on the surface of the image carrier formed by the exposure device to form a toner image In the image forming apparatus, the charging device is the charging device according to any one of claims 1 to 10.

  According to the present invention, a cleaning liquid is applied to the outer peripheral surface of the charging layer over the entire length in the direction of the rotation axis of the outer peripheral surface of the charging layer, so that the foreign material adhering to the outer peripheral surface is separated from the outer peripheral surface. Liquid coating means, and is slidably contacted with the cleaning liquid coating means on the downstream side in the rotation direction of the charging roller in the rotation axis direction of the outer peripheral surface of the charging layer over the entire length of the charging layer. By including a cleaning liquid recovery means for recovering the applied cleaning liquid, a charging device capable of maintaining good charging characteristics by always maintaining the outer peripheral surface of the charging roller to be a clean surface and the charging device are provided. A process cartridge and an image forming apparatus can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a schematic diagram illustrating a schematic configuration of an image forming unit of the image forming apparatus illustrated in FIG. The image forming apparatus 1 according to this embodiment includes an image forming unit 60 that forms a toner image from a desired document image. As shown in FIG. 1, the image forming unit 60 corresponds to four colors of yellow (Y), magenta (M), cyan (C), and black (K) as an image carrier having a photosensitive layer on the surface. The drum-shaped photoconductors 61 corresponding to the number of minutes are provided.
Further, around each photoconductor 61, a charging device 100 for charging each photoconductor 61 almost uniformly, and exposure for forming an electrostatic latent image by exposing the charged photoconductor 61 with laser light L. An apparatus 70, a developing device 63 that contains developer of four colors, yellow, magenta, cyan, and black, and forms a toner image corresponding to the electrostatic latent image on the photoreceptor 61; And a cleaning device 64 for removing residual toner.
Further, the image forming apparatus 1 includes a roller-shaped primary transfer device 62 that transfers a toner image on the photoconductor 61, an endless belt-shaped intermediate transfer member 50 to which the toner image on the photoconductor 61 is transferred, and an intermediate A secondary transfer device 51 for transferring the toner image of the transfer body 50 onto the recording paper; and a fixing device 80 for fixing the toner image on a recording medium such as a recording paper to which the toner image of the intermediate transfer body 50 is transferred. . The recording medium is conveyed from one of the paper feeding devices 26 and 27 that store the recording medium one by one to the registration roller 23 by the conveyance roller in the conveyance path 28, where it is synchronized with the toner image on the photoconductor 61. Is measured and conveyed to the transfer position.

As shown in FIG. 1, the exposure device 70 in the image forming apparatus 1 has photoconductivity by irradiating the surface of the photoreceptor 61 uniformly charged by the charging device 100 with a light beam L corresponding to the document image. An electrostatic latent image is formed on the photoreceptor 61. The light beam L may be a laser beam or the like by a lamp such as a fluorescent lamp or a halogen lamp, or a semiconductor element such as an LED or LD. Here, an LD element is used when irradiation is performed in synchronization with the rotation speed of the photosensitive member 61 by a signal from an image processing unit (not shown).
The developing device 63 includes a developing roller that is a developer carrying member, and the toner stored in the developing device 63 is conveyed to a stirring unit by a supply roller, and is mixed and stirred with a developer including a carrier. 61 is conveyed to the development area facing 61. At this time, the positively or negatively charged toner is transferred to the electrostatic latent image on the photoreceptor 61 and developed. The developer may be a magnetic or non-magnetic one-component developer or a combination thereof, or a wet developer.
The primary transfer device 62 transfers the toner image developed on the photoreceptor 61 to the intermediate transfer member 50 by forming an electric field having a polarity opposite to the polarity of the toner from the back side of the intermediate transfer member 50. The primary transfer device 62 may be any one of a corotron, a scorotron corona transfer device, a transfer roller, and a transfer brush. Thereafter, in synchronization with the recording medium conveyed from the paper feeding device 26 or 27, the toner image is transferred onto the recording medium by transfer by the secondary transfer device 51 again. Here, the first transfer may be performed directly on the recording medium instead of the intermediate transfer member 50.

The fixing device 80 heats and / or pressurizes the toner image on the recording medium to fix and fix the toner image on the recording medium. Here, the toner is passed between the pair of pressure rollers 80b and the fixing roller 80a, and at this time, heat and pressure are applied to fix the toner while the toner binder resin is melted. The pressure roller 80b and the fixing roller 80a of the fixing device 80 may be in a belt shape instead of a roller shape, or may be fixed by heat irradiation with a halogen lamp or the like.
The cleaning device 64 for the photoconductor 61 cleans and removes the toner remaining on the photoconductor 61 without being transferred, and enables the next image formation. The cleaning device 64 may be any system such as a blade made of rubber such as urethane or a fur brush made of fiber such as polyester.

Hereinafter, the operation of the image forming apparatus 1 according to the present embodiment will be described.
The reading unit 30 sets a document on the document table of the document transport unit 36, or opens the document transport unit 36 to set a document on the contact glass 31, closes the document transport unit 36, and presses the document. When a start switch (not shown) is pressed, the original is conveyed onto the contact glass 31 when the original is set on the original conveying section 36, and immediately after the original is set on the other contact glass 31, the first The first reading traveling body 32 and the second reading traveling body 33 travel. Then, light is emitted from the light source by the first reading traveling body 32 and reflected light from the document surface is further reflected toward the second reading traveling body 33 and reflected by the mirror of the second reading traveling body 33 to form an image. The image information is read through the lens 34 into the CCD 35 which is a reading sensor.
The read image information is sent to this control unit. Based on the image information received from the reading unit 30, the control unit controls the LD or LED (not shown) disposed in the exposure device 70 of the image forming unit 60 to write the laser beam L toward the photosensitive member 61. Irradiate. By this irradiation, an electrostatic latent image is formed on the surface of the photoreceptor 61.

The paper feeding unit 25 feeds the recording medium from the multi-stage paper feeding cassette 26 by the paper feeding roller, separates the fed recording medium by the separation roller, and feeds it to the paper feeding path 28, so as to be fed to the paper feeding path of the image forming unit 60. The recording medium is conveyed by a conveyance roller.
In addition to the paper feed unit 25, manual paper feed is also possible. A manual feed tray for manual feed and a separation roller for separating the recording medium on the manual tray one by one toward the manual feed path are also provided on the side of the apparatus. I have. Each of the registration rollers 23 discharges only one recording medium placed on the paper feed cassette 26 and sends it to a secondary transfer unit positioned between the intermediate transfer member 50 and the secondary transfer device 51.
When the image forming unit 60 receives the image information from the reading unit 30, the latent image is formed on the photosensitive member 61 by performing the laser writing or developing process as described above.
The developer in the developing device 63 is drawn up and held by a magnetic pole (not shown) to form a magnetic brush on the developing roller 63a. Further, the toner is transferred to the photosensitive member 61 by the developing bias voltage applied to the developing roller 63a, and the electrostatic latent image on the photosensitive member 61 is visualized to form a toner image. As the developing bias voltage, an AC voltage and a DC voltage are superimposed.
Next, one of the paper feed rollers of the paper feed unit 25 is operated to feed a recording medium having a size corresponding to the toner image. Along with this, one of the support rollers 53, 54 and 55 is rotationally driven by the drive motor, the other two support rollers are driven to rotate, and the intermediate transfer member 50 is rotated and conveyed. At the same time, the photoreceptor 61 is rotated by each image forming unit to form black, yellow, magenta, and cyan single-color images on the photoreceptor 61, respectively. Then, along with the conveyance of the intermediate transfer member 50, these single color images are sequentially transferred to form a composite color toner image on the intermediate transfer member 50.

On the other hand, one of the paper feed rollers of the paper feed unit 25 is selectively rotated, the recording medium is fed out from one of the paper feed cassettes 26, separated one by one by the separation roller, and put into the paper feed path 28, and then fed by the transport roller. The recording medium is guided to the paper feed path in the image forming unit 60 of the image forming apparatus 1, and the recording medium is abutted against the registration roller 23 and stopped. Then, the registration roller 23 is rotated in time with the composite color toner image on the intermediate transfer member 50, and the recording medium is sent to the secondary transfer portion which is a contact portion between the intermediate transfer member 50 and the secondary transfer device 51. The toner image is secondarily transferred and recorded on the recording medium due to the influence of the secondary transfer bias and the contact pressure formed in the secondary transfer portion. Here, the secondary transfer bias is preferably a direct current.
The recording medium after the image transfer is sent to the fixing device 80 by the transport belt of the secondary transfer device, and the fixing device 80 fixes the toner image by applying pressure and heat by the pressure roller, and then the discharging roller 41. The paper is discharged onto the paper discharge tray 40. In the present embodiment, the image forming unit 60 constitutes a process cartridge.
As a process cartridge according to the present invention, at least the photosensitive member 61 and the charging device 100 are integrally configured, and the process cartridge is integrated with the image forming apparatus and can be freely attached to and detached from the image forming apparatus. In addition to the photosensitive member 61 and the charging device 100, the process cartridge 3 according to the present invention may be configured integrally with a cleaning device 64 and a developing device 63 as shown in FIG.

As shown in FIG. 3, the cleaning device 64 includes a coating member 64b for applying a solid lubricant 64a to the surface of the photoconductor 61, a cleaning member 64c for removing toner remaining on the surface of the photoconductor 61, and an auxiliary cleaning member 64d. It has.
As described above, the toner remaining on the photoconductor 61 without being transferred to the recording medium after the toner image on the photoconductor 61 is transferred to the recording medium is collected by the cleaning member 64c. Thereafter, in order to prevent toner and toner constituent materials from adhering to the surface of the photoconductor 61, a solid lubricant 64a is uniformly applied on the photoconductor 61 by the application member 64b to form a lubricant layer. Further, the toner that could not be collected by the cleaning member 64c is collected by the auxiliary cleaning member 64d and conveyed to a waste toner collecting unit (not shown).
The auxiliary cleaning member 64d has a roller shape and a brush shape, and the solid lubricant 64a is made of a non-adhesive material such as a fatty acid metal salt such as zinc stearate, polytetrafluoroethylene, or the like that reduces the friction coefficient on the photoreceptor 61. What is necessary is just to be able to provide the property. Examples of the cleaning member 64c include a blade made of rubber such as silicon and urethane, and a fur brush made of fiber such as polyester.

Next, the charging device 100 according to the first embodiment of the present invention will be described. As described above, the charging device 100 uniformly charges the surface of the photoreceptor 61 in order to form an electrostatic latent image by the exposure L corresponding to the image information from the exposure device 70.
The charging device 100 according to the first embodiment of the present invention includes a charging roller 101 that charges the surface of the photoreceptor 61 in a non-contact state, and a cleaning unit 103 that cleans the outer peripheral surface of the charging roller, which will be described later.
As shown in FIG. 4, the charging roller 101 has a cored bar 101b made of a conductive material such as a metal serving as a rotating shaft 101a at the center, and an electric having a predetermined electrical resistance described later formed on the cored bar 101b. A charging layer 101c having a resistance adjustment layer 101c1 and a protective layer 101c2 formed on the outer periphery of the electrical resistance adjustment layer 101c1 and protecting the electrical resistance adjustment layer 101c1.

At both axial ends of the charging layer 101c (see FIG. 5), a gap holding member 102 made of a ring-shaped plastic material having a diameter larger than that of the charging layer 101c is coaxially connected to the charging layer 101c on the rotating shaft 101a. (See FIG. 5). The charging roller 101 is disposed such that the rotation shaft 101a thereof is orthogonal to the rotation direction (movement direction) (arrow A) of the photosensitive member 61. The outer peripheral surface 102a of the gap holding member 102 is By contacting the surface 61a of the photosensitive member 61, as will be described later, the outer peripheral surface 101c3 of the charging layer 101c and the surface 61a of the photosensitive member 61 are separated from each other by a predetermined gap G so that the charging layer 101c faces in a non-contact state. It is like that. When a desired voltage is applied to the charging layer 101c through the cored bar 101b, an electric field is generated on the outer peripheral surface 101c3 of the charging layer 101c to uniformly charge the surface 61a of the photoreceptor 61. When foreign matter such as toner, paper powder, or a damaged member adheres to the outer peripheral surface 101c3 of the charging layer 101c, an abnormal discharge that preferentially generates discharge occurs because the electric field concentrates on the foreign matter portion such as toner.
On the other hand, when an electrically insulating foreign material adheres to a wide range, no discharge occurs in that portion, and charging spots occur on the photoreceptor 61. For this purpose, in the charging device 100 according to the present invention, as shown in FIG. 4, a cleaning means 103 is provided for removing contamination on the outer peripheral surface 101c3 of the charging layer 101c.
The cleaning unit 103 includes an application roller 104 that applies a cleaning liquid 106 that separates foreign matter adhering to the outer peripheral surface 101c3 of the charging layer 101c from the outer peripheral surface 101c3, and an outer periphery of the charging layer 101c. And a cleaning liquid recovery roller 105 that recovers the cleaning liquid 106 applied to the surface 101c3.

The present invention is characterized by the arrangement of the cleaning means 103. A first embodiment of the cleaning means 103 will be described with reference to FIGS.
FIG. 4 is a cross-sectional view showing a schematic configuration of the charging device according to the first embodiment of the present invention, and FIG. 5 is a cross-sectional view taken on the application roller of FIG.
As shown in FIG. 4, the cleaning unit 103 according to this embodiment includes a coating roller 104 that rotates while contacting the charging roller 101 that rotates in the direction of arrow B (the direction of arrow C), and rotation of the charging roller 101. A cleaning liquid recovery roller 105 is provided on the downstream side in the direction B and rotates in the opposite direction (arrow D direction) to the rotation direction (B direction) of the charging roller 101. Further, the application roller 104 is disposed so that the rotation shaft 104 a thereof is parallel to the rotation shaft 101 a of the charging roller 101. The application roller 104 stores the cleaning liquid 106 on the application roller 104. A cleaning liquid supply unit 107 is provided.

The application roller 104 has a cleaning liquid holding layer 104c that is made of a foam and absorbs and holds the cleaning liquid on the outer periphery of the cored bar 104b serving as the rotation shaft 104a located at the center as described later. The outer peripheral surface 104c1 of the cleaning liquid holding layer 104c is elastically brought into contact with the outer peripheral surface 101c3 of the charging layer 101c of the charging roller 101 and the outer peripheral surface 102a of the gap holding member 102 (hereinafter referred to as the outer peripheral surface 101d of the charging roller). . Then, as shown in FIG. 5, the application roller 104 rotates in mesh with a rotation gear 101e that rotates a charging roller 101 that rotates by meshing with a rotation gear 61c attached to a rotation shaft 61b of a photosensitive drum 61 that rotates. The gear 104f is rotated at a predetermined speed.
Therefore, the rotation of the application roller 104 causes the cleaning liquid 106 to be applied to the outer peripheral surface 101d of the charging roller 101 while absorbing and holding a predetermined amount of the cleaning liquid 106 from the cleaning liquid supply unit 107 in the cleaning liquid holding layer 104c. ing. In this case, it is preferable that the rotation speed of the application roller 104 is equal to the rotation speed of the charging roller 101 or that a linear speed difference is generated with respect to the linear speed of the charging roller 101.

As shown in FIG. 5, the application roller 104 is pressed by the pressing springs 104 e at the bearing portions 104 d at both ends, and the cleaning liquid holding layer 104 c presses against the outer peripheral surface 101 d of the charging roller 101 and the outer peripheral surface 101 d of the charging roller 101. It is designed to be applied to the entire circumference of
In this case, the cleaning liquid holding layer 104c of the application roller 104 forms a coating portion of the application roller 104, and not only the outer peripheral surface 101c3 of the charging layer 101c but also the outer peripheral surface 102a of the gap holding member 102 is cleaned. The liquid 106 is applied. In this way, by applying the cleaning liquid 106 to the entire outer peripheral surface 101 d of the charging roller 101, foreign matters such as toner and paper dust adhering to the outer peripheral surface of the charging roller 101 are removed from the outer peripheral surface 101 d of the charging roller 101. Separated and separated, and held in the cleaning liquid 106.
In this way, the cleaning liquid 106 applied to the outer peripheral surface 101 d of the charging roller 101 is absorbed and held by the collection roller 105 disposed on the downstream side in the rotation direction of the applying roller 104, and the outer peripheral surface 101 d of the charging roller 101. Recovered from. As shown in FIG. 4, the collection roller 105 has a cleaning liquid absorbing layer 105c made of a foam on a cored bar 105b serving as a rotating shaft 105a disposed in parallel with the rotating shaft 101a of the charging roller 101. . As shown in FIG. 4, the cleaning liquid absorbing layer 105c elastically deforms the contact surface with the outer peripheral surface 101d of the charging roller 101 by the spring member 105f that presses the bearing portion 105d of the rotating shaft 105a. A nip portion N is formed.
As a result, the cleaning liquid 106 is reliably recovered from the outer peripheral surface 101d of the charging roller 101 by sliding in contact with the outer peripheral surface 101d of the charging roller 101 and rotating the recovery roller 105 in the opposite direction to the charging roller 101 by a driving means (not shown). It becomes possible to do.

In the recovery roller 105 in which the cleaning liquid 106 collected from the outer peripheral surface 101d of the charging roller 101 is absorbed and held in the cleaning liquid absorption layer 105c, the cleaning liquid absorption layer 105c contacts the outer peripheral surface 108d of the cleaning liquid transfer roller 108. The cleaning liquid 106 in contact with and held in the cleaning liquid absorbing layer 105 c is transferred to the outer peripheral surface 108 d of the cleaning liquid transfer roller 108.
As shown in FIG. 4, the cleaning liquid transfer roller 108 has a cleaning liquid transfer layer 108 c formed on the rotation shaft 108 a disposed in parallel with the rotation shaft 105 a of the collection roller 105. The cleaning liquid transfer layer 108c is a metal or resin drum-like body having a flat outer peripheral surface 108 on the rotating shaft. Therefore, the cleaning liquid is recovered from the recovery roller 105 by applying and transferring the outer peripheral surface 108d of the cleaning liquid transfer layer 108c of the cleaning liquid transfer roller 108 with the cleaning liquid absorbed and retained by the cleaning liquid absorption layer 105c of the recovery roller 105. is doing.
The cleaning liquid 106 transferred and collected by the cleaning liquid transfer roller 108 in this manner is transferred to a cleaning liquid receiving portion 109 disposed below the cleaning transfer roller 108 by the rotation of the transfer roller 108 and collected. . The cleaning liquid 106 collected in the cleaning liquid receiving unit 109 is subjected to necessary filtration to remove foreign substances and supplied to the cleaning liquid supply unit 107 for circulation.

As the cleaning liquid 106 used in the present invention, water that separates paper dust, toner, and the like from the outer peripheral surface 101d of the charging roller 101, an organic liquid such as a dilute solvent that swells or dissolves the toner, and the like can be used. Although there is no particular limitation, aliphatic oxygen compounds such as ethanol and acetone, and aromatic compounds such as toluene are preferable.
The cleaning liquid holding layer 104c of the application roller 104 in the present embodiment is formed by integrally molding a foam (sponge) made of resin such as polyurethane, PVC sponge, PVA, cellulose, melamine, polyethylene, etc. on the core metal 104b. can do. In particular, in the case of forming with an open-cell foam such as polyurethane, PVC sponge, PVA, or cellulose having high water absorption, the cleaning liquid is well absorbed and retained, which is preferable. A foam having low water absorption is not preferable because its holding power is small, and it becomes difficult to recover when excessive water or a dilute solvent is supplied to the outer peripheral surface 101 d of the charging roller 101.
Similarly, the cleaning absorbent layer 10105c of the cleaning liquid recovery roller 105 disposed downstream is also formed by integrally molding a foam made of resin such as polyurethane, PVC sponge, PVA, cellulose or the like on the metal core 105 with high water absorption. Formed.

In addition, the charging device 100 according to the present embodiment includes a power source that applies a voltage to the electric resistance adjustment layer 101c1 of the charging roller 101 through the cored bar 101b. The voltage may be only a DC voltage, but a voltage obtained by superimposing a DC voltage and an AC voltage is preferable. When there is a portion where the layer configuration of the electric resistance adjusting layer 101c1 is not uniform, the surface potential of the photosensitive member 61 may be uneven when only a DC voltage is applied.
With the superimposed voltage, the surface of the electric resistance adjusting layer 101c1 becomes equipotential, so that the discharge is stable and the photoreceptor 61 can be charged uniformly. The alternating voltage in the superimposed voltage preferably has a peak-to-peak voltage that is at least twice the charging start voltage of the photoreceptor 61. The charging start voltage is an absolute value of a voltage at which the photosensitive member 61 starts to be charged when only a direct current is applied to the electric resistance adjusting layer 101c. Thereby, reverse discharge from the photoconductor 61 to the electric resistance adjusting layer 101c occurs, and the photoconductor 61 can be uniformly charged in a more stable state by the smoothing effect.
Further, it is desirable that the frequency of the AC voltage is 7 times or more the peripheral speed (process speed) of the image carrier. By setting the frequency to 7 times or more, the moire image cannot be recognized (visually).

Further, as shown in FIG. 5, the charging roller 101 of the charging device 100 according to the present embodiment is configured such that the outer peripheral surface 101 d of the charging layer 101 c and the surface of the photosensitive member 61 are opposed to the photosensitive member 61 by the gap holding member 102. A small gap G is provided between 61a and 61a. The gap G is formed by bringing the outer peripheral surface 102 a of the gap holding member 102 into contact with the non-image forming area S 2 that is out of the image forming area S 1 of the photoreceptor 61.
By bringing the outer peripheral surface 102a of the gap holding member 102 into contact with the photosensitive region Z of the photoreceptor 61, variation in the gap G can be prevented even if the coating thickness of the photosensitive layer on the photoreceptor surface 61a varies.
As shown in FIG. 4, in the charging roller 101, an electric resistance adjusting layer 101c1 and a protective layer 101c2 are formed integrally with a core metal 101b on a core metal 101b made of a conductive member such as metal. The shape of the electric resistance adjusting layer 101c1 is preferably cylindrical so that the opposing surface can always change with respect to the rotation of the photosensitive member 61, and both ends are supported rotatably by gears or bearings. preferable. As described above, when the electric resistance adjusting layer 101c1 is formed with a curved surface gradually separating from the closest portion to the photosensitive member 61 in the upstream and downstream of the moving direction of the photosensitive member 61 (in the direction of arrow B), the photosensitive member 61 is removed. It can be charged more uniformly. If there is a sharp portion in the electrical resistance adjusting layer 101c1 facing the photoconductor 61, the electric potential of that portion becomes high, so discharge is preferentially started, and uniform charging of the photoconductor 61 becomes difficult.

Accordingly, the photosensitive member 61 can be uniformly charged by having a cylindrical shape and a curved surface. Further, the discharged surface of the electric resistance adjusting layer 101c1 is subjected to strong stress. Since the discharge always occurs on the same surface, its deterioration is promoted and may be scraped off. Therefore, if the entire surface of the electric resistance adjusting layer 101c1 can be used as a discharge surface, it can be used over a long period of time by preventing the early deterioration by rotating. The gap G between the charging layer 101 c of the charging roller 101 and the photosensitive member 61 is set to 100 μm or less, particularly about 5 to 70 μm, by the gap holding member 102. Thereby, formation of an abnormal image at the time of operation of charging device 100 can be suppressed.
When the gap G is 100 μm or more, the distance to reach the photosensitive member 61 becomes longer, so that the discharge start voltage according to Paschen's law becomes larger, and further, the discharge space to the photosensitive member 61 becomes larger. In order to charge the body 61 to a predetermined level, a large amount of discharge products are required due to the discharge, which remains in the discharge space even after image formation and adheres to the photoreceptor 61, causing deterioration of the photoreceptor 61 over time. It becomes a cause to promote. If the gap G is small, the reach to the photoconductor 61 is short, and the photoconductor 61 can be charged even if the discharge energy is small. However, the space formed by the charging layer 101c and the photoreceptor 61 becomes narrow, and the air flow becomes worse. Therefore, since the discharge product formed in the discharge space stays in this space, a large amount remains in the discharge space after image formation and adheres to the photoconductor 61 as in the case where the gap G is large. This causes the deterioration of the photoreceptor 61 with time. Accordingly, it is preferable to reduce the discharge energy to reduce the generation of discharge products and to form a space that does not retain air. Therefore, the gap G is preferably 100 μm or less and in the range of 5 to 70 μm. Thereby, the generation of streamer discharge can be prevented, the generation of discharge products can be reduced, the amount deposited on the photoreceptor 61 can be reduced, and spotted image spots / image flow can be prevented.

Here, the toner remaining on the photoconductor 61 after the transfer is cleaned by a cleaning device 64 provided to face the photoconductor 61, but it is difficult to completely remove the toner, and a very small amount of toner is removed from the cleaning device. 64 passes through the charging device 100. At this time, if the particle diameter of the toner is larger than the gap G, the toner may be rubbed and heated by the rotating photoreceptor 61 or the charging layer 101c, and may be fused to the outer peripheral surface 101c3 of the charging layer 101c. Since the portion where the toner is fused is close to the photosensitive member 61, abnormal discharge that causes preferential discharge occurs. Therefore, the gap G is preferably larger than the maximum particle size of the toner used in the image forming apparatus 1.
Further, as shown in FIG. 5, the charging roller 101 is fitted into a bearing portion 101f provided on a side plate of a housing (not shown) of the charging device 100, and the bearing portion 101f is formed of a resin having a low friction coefficient that is not driven. It is pressed toward the surface of the photoreceptor 61 by a compression spring 110 locked to the portion 101f. As a result, a constant gap G can be formed even if there is mechanical vibration or deviation of the cored bar.
The pressing load is 4 to 25N. Preferably, it is 6-15N. Even when the charging layer 101c is fixed by the bearing portion 101f, the size of the gap G varies due to vibration during rotation, eccentricity of the charging layer 101c, and unevenness of the surface, and the gap G deviates from an appropriate range. For this reason, the deterioration of the photoreceptor 61 is promoted over time.

Here, the load means all loads applied to the photoconductor 61 through the gap holding member 103. This can be adjusted by the force of the compression springs 110 provided at both ends of the charging roller 101, the weight of the cleaning means 103 such as the electric charging roller 101 and the application roller 104, and the like. When the load is small, fluctuation due to rotation of the charging roller 101 and jumping up due to an impact force of a driving gear or the like cannot be suppressed. When the load is large, the friction between the rotating shaft 101a of the charging roller 101 and the bearing portion 110 to be fitted increases, and the amount of wear over time is increased to promote fluctuation. Therefore, by setting the load in the range of 4 to 25 N, preferably 6 to 15 N, the gap G is set in an appropriate range, the generation of discharge products is reduced, and the amount deposited on the photoreceptor 61 is reduced. It is possible to extend the life of the photoreceptor 61 and to prevent spot-like abnormal images and image flows.
In the gap holding member 102, the outer peripheral surface 102 a of the gap holding member 102 has a height difference with the charged layer 101 c to form a gap G. As a method for forming the gap G, when removing the outer peripheral surface of the electric resistance adjusting layer 101c1 of the charging layer 101C and the gap holding member 102 by cutting, grinding or the like, these removing processes are performed simultaneously. Can be formed reliably. As a result, the gap G can be formed with high accuracy by simultaneously processing the gap holding member 102 and the electric resistance adjusting layer 101c1.
In this case, the diameter of the inscribed edge with the electrical resistance adjustment layer 101c1 of the outer peripheral surface 102a of the portion adjacent to the electrical resistance adjustment layer 101c1 of the gap holding member 102 is the same as or smaller than the diameter of the electrical resistance adjustment layer 102c1. By forming, the contact width between the gap holding member 102 and the photoconductor 61 is reduced, and the gap G between the charging roller 101 and the photoconductor 61 can be made highly accurate.

By doing so, it is possible to prevent protrusions such as burrs that are easily formed on the side end portion of the electric resistance adjusting layer 101c1 of the gap holding member 102 from coming into contact with the photoconductor 61, and through this side end portion. Thus, it is possible to prevent the adjacent electric resistance adjusting layer 101c1 from contacting the photoconductor 61 and generating a leak current.
Further, by machining the end of the gap holding member 102 on the side of the electric resistance adjusting layer 101c1 to have a small diameter, it is possible to provide a clearance (cut-off process) of a cutting blade or the like when removing this part. The shape of the clearance allowance (relief processing) may be any shape as long as the outer surface of the end portion of the gap holding portion does not contact the image carrier.
Further, when the protective layer 101c2 is formed on the surface of the electric resistance adjusting layer 101c1, it is difficult to perform masking at the boundary between the electric resistance adjusting layer 101c1 and the gap holding member 102 in consideration of variations. Therefore, in the present embodiment, when the step is formed between the electric resistance adjusting layer 101c1 and the gap holding member 102, the gap inside the gap holding portion 102 that is the same as or smaller than the electric resistance adjusting layer 101c1 is formed. By forming the protective layer 101c2 up to the contact edge, the protective layer 101c2 can be reliably formed on the electric resistance adjusting layer 101c1.

A necessary characteristic of the gap holding member 102 is to form the gap G with the photoreceptor 61 stably over the environment and for a long time (time). For this purpose, the hygroscopicity and the wear resistance are small. Material is desirable. In addition, it is important that the toner and the toner additive do not easily adhere to each other, and that the photosensitive member is not abraded because it contacts and slides on the photosensitive member, and is appropriately selected according to various conditions. Is.
Specifically, general-purpose resins such as polyethylene (PE), polypropylene (PP), polyacetal (POM), polymethyl methacrylate (PMMA), polystyrene (PS) and copolymers thereof (AS, ABS), polycarbonate (PC ), Urethane, fluorine (PTFE) and the like. In particular, in order to securely fix the gap holding member 102, an adhesive can be applied and bonded. The gap holding member is preferably an insulating material, and preferably has a volume resistivity of 10 ¹³ Ωcm or more. The reason why insulation is necessary is to eliminate the occurrence of leakage current with the photoreceptor 61. The gap holding member 102 is formed by a molding process.

The electric resistance adjusting layer 101c1 of the charging roller 101 is formed of a thermoplastic resin composition in which a polymer type ion conductive material is dispersed. The volume resistivity of the electric resistance adjusting layer 101c1 is preferably 10 ⁶ to 10 ⁹ Ωcm. If it exceeds 10 ⁹ Ωcm, charging ability and transfer ability are insufficient, and if the volume resistivity is lower than 10 ⁶ Ωcm, leakage due to voltage concentration on the entire photoconductor occurs.
The thermoplastic resin used for the electrical resistance adjusting layer 101c1 is not particularly limited, but polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS) and a copolymer thereof (AS , ABS), polyamide, polycarbonate (PC) and the like are preferable because they can be easily molded. The polymer type ion conductive material dispersed in the thermoplastic resin is preferably a polymer compound containing a polyether ester amide component.
Polyether ester amide is an ion conductive polymer material, and is uniformly dispersed and immobilized at a molecular level in a matrix polymer. Therefore, there is no variation in resistance value due to poor dispersion as seen in a composition in which an electron conductive conductive agent such as metal oxide or carbon black is dispersed. In addition, when a high applied voltage is applied as a conductive member, in the case of an electron conductive conductive agent, a path through which electricity easily flows locally is formed, so that a leakage current to the image carrier is generated, and the charging member In this case, a white / black spot image that is an abnormal image is generated. Since polyether ester amide is a polymer material, bleeding out hardly occurs. About a compounding quantity, since it is necessary to make resistance value into a desired value, it is necessary to make a thermoplastic resin into 20 to 70 weight% and a polymeric ion conductive agent to 80 to 20 weight%.

Furthermore, an electrolyte (salt) can be added to adjust the resistance value. Examples of the salt include alkali metal salts such as sodium perchlorate and lithium perchlorate, and quaternary phosphonium salts such as ethyltriphenylphosphonium / tetrafluoroborate and tetraphenylphosphonium / bromide. The conductive agent may be used alone or in combination as long as the physical properties are not impaired.
In order to uniformly disperse the conductive material in the matrix polymer at the molecular level, the addition of a compatibilizing agent enables micro-dispersion of the conductive material. Therefore, a compatibilizing agent may be appropriately used. In addition, an additive such as an antioxidant may be used as long as the physical properties are not impaired. There is no restriction | limiting in particular regarding the manufacturing method of a resin composition, It can manufacture easily by mixing each material, melt-kneading with a biaxial kneader, a kneader, etc.
The electric resistance adjusting layer 101c1 can be easily formed on the conductive metal core 101b by covering the conductive metal core 101b with the above-described conductive resin composition by means of extrusion molding or injection molding. Can do. If only the electric resistance adjusting layer 101c1 is formed on the conductive metal core 101b to form the charging roller 101, the toner, the additive of the toner, etc. may adhere to the electric resistance adjusting layer 101c1 and the performance may deteriorate. Such a problem can be prevented by forming the protective layer 101c2 on the electric resistance adjusting layer 101c1.

As a material for forming the protective layer 101c2, a fluorine-based resin, a silicone-based resin, a polyamide resin, a polyester resin, or the like is excellent in non-adhesiveness and is preferable in terms of preventing toner sticking. The surface layer is formed on the resistance adjusting layer by dissolving the surface layer constituting material in an organic solvent to prepare a paint, and various coating methods such as spray coating, dipping, and roll coating. About a film thickness, about 10-30 micrometers is desirable.
As the protective layer material, either one-component or two-component paint can be used, but environmental resistance, non-adhesiveness, and releasability are improved by using a two-component paint with a curing agent. I can do it. In the case of a two-component paint, a method of crosslinking and curing the resin by heating the coating film is common. However, since the resistance adjustment layer is a thermoplastic resin, it cannot be heated at a high temperature. As the two-component paint, it is effective to use a main agent having a hydroxyl group in the molecule and an isocyanate-based resin that causes a crosslinking reaction with the hydroxyl group.
By using an isocyanate resin, a crosslinking / curing reaction occurs at a relatively low temperature of 100 ° C. or lower. As a result of investigations from the non-adhesiveness of the toner, it was confirmed that the resin is a silicone-based resin having a high non-adhesiveness of the toner, and an acrylic silicone resin having an acrylic skeleton in the molecule is particularly good.

Since the electrical characteristics (resistance value) of the conductive member in the protective layer 101c2 are important, it is necessary to make the protective layer 101c2 conductive. The conductivity can be imparted by dispersing a conductive agent in the resin material. The conductivity is not particularly limited, and conductive carbon such as kettin black EC and acetylene black, rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, oxidation treatment, etc. Conducted carbon for color, pyrolytic carbon, indium-doped tin oxide (ITO), tin oxide, titanium oxide, zinc oxide, copper, silver, germanium, and metal oxides, polyaniline, polypyrrole, polyacetylene, etc. Examples thereof include polymers.
In addition, there are ionic conductive materials as conductivity imparting materials, inorganic ionic conductive materials such as sodium perchlorate, lithium perchlorate, calcium perchlorate, lithium chloride, and further ethyltriphenylphosphonium tetrafluoroborate And organic ionic conductive substances such as quaternary phosphonium salts such as tetraphenylphosphonium bromide, modified fatty acid dimethylammonium ethosulphate, ammonium stearate acetate, and laurylammonium acetate. The conductive agent may be used singly or as a blend of a plurality of the conductive agents as long as the physical properties are not impaired.
In this embodiment, a drum-shaped photoconductor is used as the image carrier. However, other image-carrying pairs such as a belt-like photoconductor are also effective.

Next, a charging device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view showing a schematic configuration of a charging device according to the second embodiment of the present invention.
The charging device according to the second embodiment is different from the charging device according to the first embodiment described above in the collection unit that collects the cleaning liquid 106 from the collection roller 105.
That is, as a means for collecting the cleaning liquid 106, a collecting blade 111 is used instead of the cleaning liquid transfer roller 108 of the first embodiment. The collection blade 111 is made of a metal or resin plate-like body and the like, and the cleaning liquid 106 held in the cleaning liquid absorption layer 105c is brought into pressure contact with the cleaning liquid absorption layer 105c of the collection roller 105. Is extruded onto the surface and poured into the cleaning liquid receiving portion 109. By using such a recovery blade 111, the cleaning liquid can be recovered with a simple structure.

A charging device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view showing a schematic configuration of a charging device according to the third embodiment of the present invention.
The charging device according to the third embodiment is different from the charging device according to the first embodiment described above in the collection unit that collects the cleaning liquid 106 from the collection roller 105. That is, as a means for collecting the cleaning liquid 106, a suction means 112 that sucks the cleaning liquid 106 is used instead of the cleaning liquid transfer roller 108 of the first embodiment. The suction means 112 has a nozzle 112a that is brought into pressure contact with the cleaning liquid absorption layer 105c of the recovery roller 105 and sucks the cleaning liquid 106 held in the cleaning liquid absorption layer 105c.
The cleaning liquid 106 sucked by the nozzle 112 a is filtered and fed to the cleaning liquid supply unit 107 of the application roller 104. By using such a suction means 112, it is not necessary to attach the cleaning liquid receiving portion 109 used in the first and second embodiments close to the collection roller 105, so that the size can be reduced. . In addition, the suction means 112 can reliably suck and collect the cleaning liquid held from the cleaning liquid absorption layer 105 c, and always maintain the ability of the collecting roller 105 to collect the cleaning liquid 106 from the charging roller 101. It becomes possible.

Hereinafter, specific examples and comparative examples of the present invention will be described.
<Examples and Comparative Examples>
As an electric resistance adjusting layer, ABS resin (Denka ABS GR-3000, manufactured by Denki Kagaku Kogyo) 50% by weight, polyether ester amide (IRGASTAT P18, manufactured by Ciba Specialty Chemicals) 50% by weight, polycarbonate-glycidyl methacrylate-styrene-acryloyl A resin composition obtained by mixing 4.5 parts by weight of a tolyl copolymer (Modiper CL440-G, manufactured by NOF Corporation) with a total of 100 parts by weight of polyether ester amide and ABS resin, and then melt-kneading the resin composition. The obtained resin composition was obtained by injection molding on a core metal (outer diameter 8 mm) made of a SUM alloy plated with Ni.
Then, ring-shaped gap holding members (high-density polyethylene resin (Novatech PP HY540, manufactured by Nippon Polychem)) were press-fitted into both ends of the electric resistance adjusting layer. Was finished by simultaneous processing to 12.5 mm and the outer diameter of the resistance adjusting portion to 12.4 mm.
As described above, ring-shaped void holding members (high-density polyethylene resin (Novatech PP HY540, manufactured by Nippon Polychem Co., Ltd.)) were press-fitted into both ends of the electric resistance adjusting layer with respect to the four-level electric resistance adjusting layer. By processing, the outer diameter of the gap holding member was finished at the same time to 12.5 mm and the outer diameter of the electric resistance adjusting portion was 12.4 mm, and then an acrylic silicone resin (3000 VH-P, A protective layer having a film thickness of about 10 μm was formed by spray coating a mixture consisting of Kawakami Paint), an isocyanate curing agent (Kawakami Paint), and carbon black (30% by weight based on the total solid content).
Thereafter, the coating resin was heated and cured in an oven at 80 ° C. for 1 hour to obtain a charging roller having a step difference of about 40 μm between the gap holding member and the electric resistance adjusting layer.
As shown in FIG. 8, the outer peripheral surface of the charging roller obtained by the above method, the cleaning liquid holding layer of the coating roller that cleans the outer peripheral surface, and the cleaning absorbing layer of the recovery roller are variously changed as shown in FIG. Image formation was performed using the charging device shown in one embodiment, and the image formation state was tested.

<Example 1>
In the charging roller obtained by the above method, the cleaning liquid holding layer of the application roller and the cleaning absorbing layer of the recovery roller use polyurethane foam-shaped open cell foams, and the length reaches the gap holding member. The outer diameter of both the application roller and the collection roller is 6 mm. Further, an ethanol aqueous solution was used as the cleaning liquid.
The application roller and the collection roller are rotated by gear driving in conjunction with the driving of the charging roller 101, and the collection roller is rotated in the reverse direction with respect to the rotation direction of the charging roller. The linear speed ratio between the application roller and the charging roller is 1.5: 1. In addition, a transfer roller made of ABS resin was used in the cleaning liquid absorbing layer of the recovery roller.
<Example 2>
In Example 1, the cleaning liquid contained in the coating roller was changed to acetone and tested.
<Example 3>
In Example 1, the cleaning liquid contained in the coating roller was changed to water and tested.
<Example 4>
In Example 1, the cleaning liquid contained in the coating roller was changed to water, and the linear velocity ratio between the coating roller and the charging roller was changed to 1: 1, and the test was performed.
<Example 5>
In Example 1, the cleaning liquid contained in the coating roller was changed to water, and the linear velocity ratio between the coating roller and the charging roller was changed to 0.75: 1.
<Example 6>
In Example 1, the cleaning liquid holding layer of the application roller and the cleaning absorption layer of the recovery roller were changed to melamine and polyurethane foams, respectively, and the test was performed.
<Example 7>
In Example 1, the materials for the cleaning liquid holding layer of the application roller and the cleaning absorption layer of the recovery roller were changed to melamine and polyurethane, respectively, and changed to acetone as the cleaning liquid to be contained in the application roller, and the test was performed.
<Example 8>
In Example 1, the cleaning liquid holding layer of the application roller and the cleaning absorption layer of the recovery roller were changed to melamine and polyurethane, respectively, and the cleaning liquid contained in the application roller was changed to water, and the test was performed.
<Example 9>
In Example 1, the material of the cleaning liquid holding layer of the application roller and the cleaning absorption layer of the recovery roller is changed to cellulose, changed to water as the cleaning liquid contained in the application roller, and the linear speed ratio of the application roller is set to 1: The test was changed to 1.
<Example 10>
In Example 1, melamine was used as a material for the cleaning liquid holding layer of the application roller and the cleaning absorption layer of the recovery roller, and the test was performed.
<Example 11>
The test was performed by setting the lengths of the cleaning liquid holding layer of the application roller and the cleaning absorption layer of the recovery roller in Example 1 so as to be in a region not reaching the gap holding member.
<Example 12>
The lengths of the cleaning liquid holding layer of the application roller and the cleaning absorbing layer of the recovery roller in Example 1 were set so as to be an area not reaching the gap holding member, and the test was performed by changing to acetone as the cleaning liquid.
<Comparative Example 1>
In Example 1, the cleaning liquid holding layer made of melamine resin is set so that the cleaning liquid holding layer of the coating roller does not use the cleaning liquid and the recovery roller, and the length of the cleaning liquid holding layer of the coating roller is set so as not to reach the gap holding member. The test was performed using only the application roller (in a state where the cleaning liquid is not held), and the linear velocity ratio between the application roller and the charging roller was 1: 1.
<Comparative example 2>
In Example 1, the cleaning liquid and the collection roller are not used, and only the application roller having the cleaning liquid holding layer (having a length reaching the charging layer and the gap holding member) made of melamine resin is used (the cleaning liquid is removed). The condition was not held).

The image was evaluated by mounting the process cartridge and the charging devices obtained in Examples 1 to 12 and Comparative Examples 1 and 2 on the image forming apparatus shown in FIG. 1 as a process cartridge integrally configured with a photoconductor. . The voltage applied to the charging roller was DC = −700 V and AC = 2200 Vpp (frequency = 2 kHz). The evaluation environment was 23 ° C. and 60% RH. In addition, the presence or absence of an abnormal roller image after a predetermined number of sheets passed, the surface state of the roller, and the entry of toner into the gap holding member were confirmed.
The evaluation results are shown in FIG. In FIG. 9, the evaluation of abnormal images, foreign matter adhesion to the outer peripheral surface of the charging layer, and foreign matter adhesion to the outer peripheral surface of the gap holding member is ○: not recognized at all, and Δ: slightly recognized. X: Displayed as being greatly recognized, and in comprehensive judgment, indicated as ◯: good, Δ: slightly good, x: poor.
As is apparent from these evaluation results, in the case of Comparative Example 1, since no cleaning liquid is used, the foreign matter adhering to the outer peripheral surface of the charging layer of the charging roller cannot be sufficiently removed. An abnormal image occurred on paper. In addition, since the cleaning liquid holding layer of the application roller has a length that does not reach the outer peripheral surface of the gap holding member, it is not possible to remove foreign matter adhering to the outer peripheral face of the gap holding member. The gap between the surface and the surface became non-uniform and abnormal images occurred frequently.

In Comparative Example 2, the cleaning liquid holding layer of the application roller contacts the charging layer of the charging roller and the outer peripheral surface of the gap holding member, but the cleaning liquid and the recovery roller are not used. Although the cleaning performance of the outer peripheral surface of the gap holding member was slightly improved, the cleaning performance of the outer peripheral surface of the charging layer and the gap holding member was insufficient, and an abnormal image was generated with a small number of sheets passing.
On the other hand, in Examples 1 to 9 according to the present invention, the application roller using a cleaning solution of water or a dilute solvent peels off the foreign matter adhering to the outer peripheral surface of the charging layer and the outer peripheral surface of the gap holding member of the charging roller. The foreign matter is collected together with the cleaning liquid by the collecting roller, and the outer peripheral surface of the charging roller is well cleaned. As a result, no abnormal image was observed even when 120 sheets were passed, and a good result was shown.
Further, in Example 10 according to the present invention, melamine resin harder than polyurethane was used as the cleaning liquid absorbing layer of the collecting roller, so that the foreign matter adhering to the outer peripheral surface of the gap holding member compared to that in Example 6 was used. Although the cleaning characteristics slightly deteriorated, the occurrence of abnormal images was improved as compared with Comparative Examples 1 and 2 in which no cleaning liquid was used.
In the examples 11 and 12, the cleaning liquid was applied only to the charging layer of the charging roller to remove the foreign matter from the charging layer. Although the cleaning characteristics of foreign matters adhering to the outer peripheral surface are deteriorated, the occurrence of abnormal images is improved as compared with Comparative Examples 1 and 2 in which no cleaning liquid is used.

1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a schematic configuration of an image forming unit of the image forming apparatus illustrated in FIG. 1. It is the schematic which shows schematic structure of the process cartridge which concerns on one Embodiment by this invention. It is sectional drawing which shows schematic structure of the charging device which concerns on 1st Embodiment by this invention. It is sectional drawing cut | disconnected on the application | coating roller of FIG. It is sectional drawing which shows schematic structure of the charging device which concerns on 2nd Embodiment by this invention. It is sectional drawing which shows schematic structure of the charging device which concerns on 3rd Embodiment by this invention. It is a table | surface figure which shows the characteristic of the application | coating roller and collection | recovery roller of the Example by this invention, and a comparative example. It is a table | surface figure which shows the characteristic evaluation result using the charging device of the Example by this invention, and a comparative example. 1 is a schematic configuration diagram of a conventional electrophotographic image forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 2 Image forming part, 3 Process cartridge, 61 Photoconductor, 62 Primary transfer apparatus, 63 Developing apparatus, 64 Cleaning apparatus, 70 Exposure apparatus, 100 Charging apparatus, 101 Charging roller, 101a Rotating shaft, 101c Charging Layer, 101c1 electric resistance adjusting layer, 101c2 protective layer, 101d outer peripheral surface, 102 gap holding member, 102a outer peripheral surface, 104 coating roller, 104a rotating shaft, 104c cleaning liquid holding layer, 105 recovery roller, 105a rotating shaft, 105c cleaning liquid Absorbing layer, 106 cleaning liquid, 107 cleaning liquid supply section, 108 cleaning liquid transfer roller, 108a rotating shaft, 108c cleaning liquid transfer layer, 109 cleaning liquid receiving section, 111 recovery blade, 112 suction member

Claims (12)

A charging roller having a charging layer for charging the surface of an image carrier formed on a rotating shaft, and a gap holding member having a larger diameter than the charging layer attached to both ends of the charging layer in the axial direction on the rotating shaft In the charging device with
A cleaning liquid applying means for applying a cleaning liquid on the outer peripheral surface of the charging layer over the entire length in the rotation axis direction of the outer peripheral surface of the charging layer;
The cleaning liquid applied to the outer peripheral surface of the charging layer is collected by sliding in contact with the cleaning liquid application unit on the downstream side in the rotation direction of the charging roller over the entire length of the outer peripheral surface of the charging layer in the rotation axis direction. A charging device comprising a cleaning liquid recovery means. The charging device according to claim 1.
An application portion of the cleaning liquid application unit is extended so as to contact the outer peripheral surface of the gap holding member, and the cleaning liquid is applied to the outer peripheral surface of the charging layer and the gap holding member. The recovery portion is extended so as to be in sliding contact with the outer peripheral surface of the gap holding member, and the cleaning liquid applied to the outer peripheral surface of the charging layer and the gap holding member is recovered. apparatus. The charging device according to claim 1 or 2,
The cleaning liquid recovery means recovers a cleaning liquid that rotates while pressing a cleaning liquid absorption layer formed on a rotation shaft disposed in parallel with the rotation shaft of the charging roller against the outer peripheral surface of the charging layer of the charging roller. A charging device having a roller and having a cleaning liquid recovery unit that recovers the cleaning liquid held in contact with the cleaning liquid absorption layer of the cleaning liquid recovery roller and held in the cleaning liquid absorption layer. The charging device according to claim 3.
A cleaning liquid transfer roller member that rotates while the cleaning liquid transfer layer is pressed against the cleaning liquid absorption layer formed on a rotation shaft disposed in parallel with the rotation axis of the cleaning liquid recovery roller. A recovery blade member that presses the front end surface against the cleaning liquid absorption layer and collects the cleaning liquid from the cleaning liquid absorption layer; and a front end part that presses against the cleaning liquid absorption layer and moves from the cleaning liquid absorption layer A charging device characterized by being a cleaning liquid recovery member of any one of suction members for sucking a cleaning liquid. The charging device according to claim 4.
The charging device is characterized in that the recovery unit is the cleaning liquid transfer roller member, and the cleaning liquid transfer roller member is rotated in the same direction as the rotation direction of the cleaning liquid recovery roller. The charging device according to any one of claims 3 to 5,
The charging device according to claim 1, wherein the cleaning liquid absorbing layer of the cleaning liquid collecting roller is made of a foam. The charging device according to claim 6, wherein
The charging device, wherein the foam is made of a resin. The charging device according to any one of claims 3 to 7,
The charging device, wherein the cleaning liquid recovery roller is rotated in a direction opposite to a rotation direction of the charging roller. The charging device according to any one of claims 1 to 8,
The cleaning liquid application means is a cleaning liquid application that rotates while contacting a cleaning liquid holding layer formed on a rotation shaft arranged in parallel with a rotation shaft of the charging roller against an outer peripheral surface of the charging layer of the charging roller. A charging device comprising a roller and a cleaning liquid supply means for supplying the cleaning liquid to a cleaning liquid holding layer of the cleaning liquid application roller. The charging device according to claim 9, wherein
The charging device, wherein the cleaning liquid holding layer is made of a foam formed of a resin. In a process cartridge that includes an image carrier and a charging device that uniformly charges the surface of the image carrier, and the charging device is configured integrally with the image carrier.
The process cartridge according to claim 1, wherein the charging device is the charging device according to claim 1. An image carrier, a charging device that uniformly charges the surface of the image carrier, and an image carrier surface charged by the charging device are irradiated with light according to image information to statically apply to the surface of the image carrier. An image forming apparatus comprising: an exposure device that forms an electrostatic latent image; and a developing device that supplies toner to the electrostatic latent image on the surface of the image carrier formed by the exposure device to form a toner image.
The image forming apparatus according to claim 1, wherein the charging apparatus is the charging apparatus according to claim 1.

Images